Illustration showing proteins (red) being synthesised by ribosomes (yellow spheres) receiving mRNA (messenger ribonucleic acid, purple and yellow strands). The instructions for building the proteins are encoded in these strands of mRNA that originate in the cell nucleus (multicoloured, centre), and is a copy of the information coded in DNA (deoxyribonucleic acid) in the nucleus. The mRNA is shown emerging from nuclear pores.